A Key to Quantum Computing, Close to Home

By Douglas Quenqua

Nov. 4, 2013

A blue dye found in many household items, including the British five-pound note, could fill an important need in the quest to develop a quantum computer, researchers say.

The dye, copper phthalocyanine, also known as CuPc, contains electrons that can spend surprisingly long times in “superposition,” a quantum term meaning that they exist in two possible states at once, like Schrödinger’s cat. The researchers made the discovery by placing the electrons in superposition using an electron spin resonance spectrometer, then watching how long it took them to decay from that state.

For quantum computing to become a reality, scientists need materials to serve as quantum bits, or qubits. Unlike the binary bits that underlie regular computing, qubits must be capable of sustaining superpositions for long periods, enabling ultrafast computation. The difficulty in maintaining complex quantum states for long periods of time is a leading reason that scientists have yet to build a quantum computer that can outperform existing computers.

The researchers focused on CuPc because it can be easily processed into a thin film for use in device fabrication, which makes it an attractive qubit candidate, said Marc Warner, a former doctoral student at the London Center for Nanotechnology and the lead author of the study, which appears in Nature. It is also low-cost and organic. “The honest answer is that we didn’t know it would work well,” he said by email.

A version of this article appears in print on , on Page D4 of the New York edition with the headline: Nanotechnology: A Key to Quantum Computing, Close to Home. Order Reprints | Today’s Paper | Subscribe